Not all sedges are weeds! Some are good garden plants, with attractive shape. If you think it looks nice, keep it. It isn't Nutsedge (the most invasive sedge).
first two are coleus. third might be some kind of ornamental grass or possibly a bamboo or something similar. i'll defer to the others about the fourth. some kind of sedge seems about right.
#3 Miscanthus sinensis ‘Cosmopolitan’? http://www.longsgarden.com/longs garden/images/53B Cosmopolitan.jpg